PHP Easy Ticket System is a full blown help desk application that you can use for support, reports, errors, feedback, or a help desk. It has administration control and users can check how their tickets are coming along.

email2trac is a utility that converts email messages to Trac tickets. It features HTML message conversion, attachments, updating of tickets via email, command line options, a configuration file, Unicode support, spam detection, workflow support, and support for FullBlogPlugin and DiscussionPlugin.